Abstract:This paper describes a work in progress on the usage of Acceptance Test-Driven Development (ATDD) during the construction of cryptographic software. As cryptography becomes universalized, it is becoming hard to separate good implementation from bad ones. The paper argues that Test Vectors for cryptography can be used as User Stories in Behavior-Driven Development (BDD) and automate ATDD during software development, complementing algorithm’s specification, and contributing to augment software reliability and the overall trust in the correctness of cryptographic implementations. The acquired confidence is preserved even after performing program transformations for improvements, such as performance optimization and hardenings.